1. Field of the Invention
The invention relates to a wire-stranded hollow coil body used as a main wire component of a medical equipment in the form of flexible line wire such as a catheter, catheter guide wire, endscope treating tool or the like, and more particularly concerns to a medical equipment produced therefrom and a method of making the wire-stranded hollow coil body.
2. Description of Related Art
In a catheter and a catheter guide wire which introduce a leading distal end into a diseased area through a twisted and turned vascular system, a leading distal end of the catheter or the catheter guide wire is inserted into the blood vessel or the somatic cavity by a “push-pull and turn” manipulation at a hand access portion located ouside a subject patient upon treating the diseased area. In an endscope treating tool which is inserted through a somatic cavity to reach the diseased area, a leading end of the endscope treating tool is manipulated in the same manner as mentioned above.
In order to achieve a smooth manipulation when inserting the leading distal end into the somatic cavity and the blood vessel, it is required for these medical devices to have multi-mechanical properties. The multi-mechanical properties includes a high flexibility, a good straightness in free state and a good restitutivity against bending deformation. The medical devices of this type are required at its leading distal end portion to have a high flexibility, while at the same time, having at its rear portion to have an appropriate rigidity as a functionally gradient property. It is also indispensable for the leading distal end to have a high maneuverability in which the leading distal end properly responds to the hand operation which is to be done outside the subject patient.
The following related art flexible linear wires used as a main component of the medical devices have been produced to achieve the above indispensable multi-mechanical properties.
In the references of Laid-open Japanese Patent Application Nos. 2002-275774 and 4-309371 (referred in turn to as “first and second reference” hereinafter), a wire-stranded hollow coil body is disclosed which have a multitude of coil line elements stranded along a predetermined circular line to form a rope-like flexible linear tube having a central axial hollow portion. In the domestic publication of Japanese Patent Application No. 2000-512691 (referred to as “third reference” hereinafter), a solid thin wire made from an elastic shape-memory alloy is stranded under a tensile load. The solid thin wire thus stranded is subjected to a stress-removing heat-treatment procedure under the condition of approx. 280° C.×30 min. −300° C.×30 min. so as to provide a flexible solid wire body used for medical devices.
The reference of Laid-open Japanese Patent Application No. 10-165361 (referred to as “fourth reference” hereinafter) discloses a helical hollow pipe to produce a sheath from an elongated hollow thin wire used for an endscope treating tool. An outer surface of the helical hollow pipe is partly ground to form a diameter-reduced portion, or partly replaced by a thin wire to provide a good bending capability with the sheath.
The reference of Laid-open Japanese Patent Application No. 11-104071 (referred to as “fifth reference” hereinafter) discloses a flexible wire sheath made from a multi-wound helical coil body used for an endscope treating tool. Into the flexible wire sheath, a manipulation wire is inserted so as to be rotatable with a biopsy end portion in unison.
The reference of Laid-open Japanese Patent Application No. 11-33004 (referred to as “sixth reference” hereinafter) discloses a pressure-sensor type guide wire in which a guide wire sensor portion is made from a stainless steel cloak tube having a platinum helical wire tube and a stainless steel helical wire tube concentrically placed to enclose a piezoelectric elongation plate. The reference of Laid-open Japanese Patent Application No. 7-213481 (referred to as “seventh reference” hereinafter) discloses a flexible endscope in which a manipulation wire is placed within a cloak tube having four flexible helical wires juxtaposed,each of which is wound to have a different helical pitch. The reference of Laid-open Japanese Patent Application No. 10-290803 (referred to as “eighth reference” hereinafter) discloses an endscope treating tool in which a flexible wire coil sheath constitutes a main structure.
In the catheter, the catheter guide wire and the endscope tube made from the wire-stranded hollow coil body disclosed by the first and second references, the wire-stranded hollow structure makes it possible to present a good flexibility based on the wire-stranded body construction per se. The wire-stranded hollow structure advantageously reduces a torsion-resistant moment upon manipulation, while at the same time, reducing a weight dimension per unit length. However, in contrast to the above advantages, the preceding references has the following drawbacks.
Namely, both the references lack a lengthwise linearity and a rotation-following capability responsive to the manipulation of the leading distal end, and have no gradient flexibility in which the wire-stranded body gradually shifts its property in the lengthwise direction while substantially maintaining uniform torsion-resistant and flexible properties among the multi-mechanical properties. The flexible solid wire body disclosed by the third reference is made from the solid thin wire deviod of the central hollow portion, this increases a torsional resistance, and adding the weight dimension per unit length too much to put the flexible solid wire body into practical use for the medical devices.
The wire-stranded hollow coil structure disclosed by the fourth to sixth references is unsatisfactory from the point of the indispensable requirement to function as a main linear body for the medical devices because both the references lack the lengthwise linearity and the rotation-following capability while maintaining the uniform torsion-resistant property and flexible property, as is the case with the first and second references.
Therefore, it is an object of the invention to overcome the above drawbacks so as to provide a wire-stranded hollow body, a medical equipment formed therefrom and a method of making the same in which the medical equipment having the flexible line wire as a main wire component is remarkably improved at its performance.